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First Semester M.Tech. Degree Examination, June 2009Branch – Electrical Engineering (2008 Scheme)

EPC 1003 : POWER QUALITY

Time : 3 Hours Max. Marks : 100

Instruction: Answer any five questions.

I. a) What is notching ? How it can be results in error in frequency measurements ? 10b) With the block diagram explain hybrid UPS and compare it with ON-line and

OFF-line UPS. 10

II. a) Explain the term ‘Area of Vulnerability’. 5b) Derive the equation for THD, TIF, DIN, C-message weights and flicker facts. 15

III. a) Explain different methods to be used for reducing EMI in power semiconductordevices. 10

b) Write short notes on harmonic distortion of fluorescent lamps. 10

IV. a) Explain the need for grounding in electrical equipments. 10b) Explain the nature of harmonic distortion produced by Arching devices. 10

V. a) Explain the basic principle of active filtering of harmonic. 5b) A six pulse converter bridge is rated at 100 KV, 100 MW dc operating at °=α 20 .

The bridge is connected to 350 KV, 50Hz ac system via a 350/110 KV convertestransformer with 20% leakage reactive. The secondary current is 613 A and thatof primary 204A. Design the filter for connecting to the primary side of the filterwith the help of following dates.a) Capacities temperature coefficient – 0.05%b) Induct temperature coefficient : 0.01 %c) Ambient temperature = C20°±d) Frequency tolerance = %1± . 15

VI. a) Explain the working of DVR with the help of control strategy. 12b) With short notes on

1) Fuse saving2) Voltage flicker. 8

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